Pump



De. 4, 1962 E. c. SWANSON PUMP 6 Sheets-Sheet 1 'INVENTOR.

Edam) C Jzuanaam BY 5 5 Filed Jan. 26, 1961 y) ollwivL Dec. 4, 1962 E. c. SWANSON PUMP Filed Jan. 26, 1961 6 Sheets-Sheet 2 15 INVENTOR.

Edam C \im Dec. 4, 1962 E. c. SWANSON 3,066,610

PUMP

Filed Jan. 26, 1961 6 Sheets-Sheet 4 I N VEN TOR.

fail/Zn C 5zz/a7w0m KM, W

Dec. 4, 1962 E. c. SWANSON PUMP 6 Sheets-Sheet 5 Filed Jan. 26, 1961 Dec. 4, 1962 E. c. SWANSON 3,066,610

PUMP

Filed Jan. 26, 1961 6 Sheets-Sheet 6 61/07 jwaizsaiz.

g I 6 zf w g ue United States Patent Orifice Patented Dec. 4, 196.2

3,966,610 PUMP Edwin C. Swanson, Rockford, Ill., assignor to Greenlee Bros. 3: (10., a corporation of Illinois Filed .Ian. 26, 1961, Ser. No. 86,248 12 Claims. (Cl. 10310) This invention relates to a pumping unit and more particularly to a portable motor driven pumping unit for operating hydraulic tools. This application is a continuation-in-part of my prior application Serial No. 584,955, filed May 15, 1956, now abandoned.

The general object of this invention is to provide a new and improved pumping unit.

An object of this invention is to provide a new and improved portable motor driven pumping unit which may be conveniently carried by a person from place to place and which may easily be hoisted into an overhead working position on a pole, if desired, for operating a hydraulic pressure tool.

Another object of this invention is to provide a pumping unit of the character described which will automatically and successively provide a relatively high volume low pressure output or a relatively high pressure low volume output, and which will hold the relatively high pressure while bypassing continually pumped fluid to a reservoir.

Another object of this invention is to provide a pumping unit of the character described having a manual control valve operable to open a passage permitting the relatively high pressure outlet fluid to pass directly to the reservoir.

Another object of this invention is to provide a new and improved pumping unit including a motor connected to a housing forming a fluid reservoir, a carrying handle on the motor, a pump disposed in the reservoir and driven by the motor, valve means for automatically providing sequentially a relatively high volume low pressure output, a relatively high pressure low volume output, and a holding of the relatively high outlet pressure, and either a manual or an automatic valve operable to release the pressure in the outlet.

A further object of this invention is to provide a pumping unit of the character described wherein the pump includes a large area sleeve piston and a small area stem piston, said pistons being concentrically arranged and connected to reciprocate together, and passage means for connecting the fluid reservoir to the inlet of the sleeve piston, for connecting the outlet of the sleeve piston to the inlet of the stern piston and .for connecting the outlet of both pistons to the pump outlet.

A further object of this invention is to provide a pumping unit of the character described wherein the two concentric pistons are carried in a piston carrier which is removably mounted in a pump housing block, the carrier having passages communicating with passages in the pump housing block, and the housing passages and the carrier passages having valving disposed therein for controlling the passage of fluid pumped by the pistons.

Other objects, features and advantages will become apparent from the following detailed description of pre ferred embodiments taken in connection with the accompanying drawings, in which:

FIGURE 1 is a broken end elevational view of a preferred embodiment of the invention partially in section;

FIGURE 2 is a broken front elevational view of the invention as shown in FIGURE 1 taken partially in section along line 22 of FIG. 3;

FIGURE 3 is a plan view of the structure shown in FIGURES l and 2;

FIGURE 4 is an enlarged fragmentary vertical sectional view taken generally along line 4-4 of FIGURE FIGURE 5 is an enlarged fragmentary vertical tional view of FIGURE 2;

FIGURE 6 is a horizontal sectional view taken orally along line 66 of FIGURE 5;

FIGURE 7 is a vertical sectional View taken orally along line 77 of FIGURE 6;

FIGURE 8 is a fragmentary enlarged vertical sectional view similar to FIGURE 4 showing a midification of a manual valve;

FIGURE 9 is a fragmentary broken vertical sectional view, similar to FIGURE 2, showing a modification of a pump having an automatic valve;

gen-

FIGURE 10 is a horizontal sectional View taken gen- While the invention herein described is a preferred embodiment, it is not intended to limit the invention to the specific forms and arrangements shown, it being contemplated that various changes may be made by. those skilled in the art without departing from the spirit of the appended claims.

This invention is directed to a portable pumping unit which is adapted to be connected to a piston and cylinder j device of a press or the like to automatically supply a large volume of pumped fluid at relative low pressure for a rapid movement of the piston when the resistance in the pump outlet is low, and a small volume of fluid at relatively high pressure for a slower movement of the piston when the resistance in the outlet is high, and to hold the high pressure in the outlet at the end of the piston movement. A manual or an automatic valve is provided to release the pressure in the pump outlet.

One such device for which this pumping unit is well adapted is a hydraulic clamping press wherein it is desired to initially provide a high volume low pressure fluid input to the device to advance the clamping diesfollowed by a relatively low volume high pressure fluid input for a high pressure clamping operation.

desired. operation as if its output were connected to such a hydraulic clamping press.

As shown in FIGURES 1, 2 and 3, the pumping unit includes an electric motor 10 secured to a housing 11' which forms a fluid reservoir having a normal fluid level indicated by the broken line X. The pumping unit is provided with a conveniently positioned electric switch 12 operable to actuate the motor and has a handle 13 secured to the top of the motor 10 which allows the pumping unit to be easily carried by hand from place to place. The handle also provides a means for attaching a cable or chain hoist to the unit so that it may be hoisted into a working position, for example, near the top of a tower or pole carrying power lines or telephone lines, so that such wires may be spliced together. The only external connection necessary for such an operation would be an electrical cable which may be conveniently connected to a portable generator on the ground.

The housing II is provided with a fill plug 14 which is used for initially filling the reservoir with fluid and for replacing any fluid lost through leakage during operation of the unit. In order to conduct the pumped fluid to the SEC- gen-

It is also desirable to automatically hold this high pressure as long as needed and then to release the pressure when i The invention will hereinafter be described in i clamping device or other piston and cylinder device to which the pump is connected, a pair of openings 15 and 16 are formed in the side of the housing 11. As shown in FIGURES 2, 4, and 6, opening has an outlet coupling 17 fitted therein which is provided with a sealing ring 18 to prevent leakage of fluid from the reservoir. In FIGURES 2, 4 and 5 the other opening 16 is shown as sealed by a bolt 19 carrying an O-ring 19' and a nut 20. The opening 16 is adapted to receive an outlet coupling similar to the coupling 17 when two outlet lines are needed with another modification of this pumping unit, which will be described hereinafter.

To provide means for pumping fluid from the reservoir to the pump outlet coupling 17, a pump, indicated generally at is disposed in the reservoir in driven relation to the electric motor 10 and includes a housing or cylinder block 26 secured by bolts 27 to an internal cylindrical flanged portion 28 of the housing 11. As the pump disclosed herein is an opposed multiple piston pump with the same structure in each piston unit, corresponding reference numerals will be used to indicate corresponding parts in each half of the pump.

The cylinder block 26 is provided with horizontally aligned cylinders 30 which open into a vertically extending circular recess 31, as best shown in H63. 2, 5 and 6. To provide a pair of pumping members in each cylinder 30, a piston carrier 32 is threadably mounted in each cylinder 30. The carriers 32 have inwardly projecting tubular or cylindrical stem portions 33 each having a diameter substantially smaller than the diameter of the cylinders 30, the cylinders 30 and the tubular portions 33 thus defining annular spaces or cylinders 34 in which are slidably mounted sleeve pistons 35 each having a relatively large pumping area. Stern or rod pistons 36, each having a relatively smaller pumping area, are slidably mounted in small cylinders 37 formed by cylindrical bushings 38 secured in each tubular portion 33. Thus, the embodiment of the pump disclosed herein is provided with two Opposed pairs of pistons, with each pair including the large sleeve piston 35 and the small stem piston 36 concentrically disposed in the cylinder block 26. The ends of each pair of pistons are secured to plates 39 so that each pair is connected for movement together, as a unit.

In order to reciprocate the pistons, a driving connection is provided between the motor 110 and the pistons, and includes a stub shaft 40 rotatably mounted in the cylindrical flange 28 by an upper ball bearing 41 and a lower ball bearing 42. The upper end of the stub shaft 40 is drivingly connected. to a downwardly extending drive shaft 43 of the motor 16 by a key 44. The lower end of the stub shaft 40 has an eccentric 45 formed thereon and rotatable in the vertically extending recess 31 formed in the cylinder block 26. The eccentric 45 carries the inner race of a ball bearing 46, the outer race of which is in contact with the plates 39 secured to the ends of each pair of pistons so as to reciprocate the pistons in the annular cylinders 34 and the small cylinders 37 when the motor 10 is operating. Springs 4'7 disposed in the annular cylinders 34 and acting against the sleeve pistons 35 are operable to urge the pistons at all times against the outer race of the ball bearing 46.

The cylinder block 26 also has fluid passages serving as intake and outlet manifolds. interconnecting passages are provided in the piston carriers 32 for alignment with the passages in the block 26 making a very compact pump unit. These passages are best seen in FIGURES 2, 5, 6 and 7. As the piston units are alternately moved toward the center of the block 26 for an intake stroke, fluid is drawn from the reservoir alternately through a pair of wire strainers 50, upwardly through conduits 51, past ball check valves 52 (FIGURE 7) and through passages 53 into the annular cylinders 34- vacated by the receding sleeve pistons 35. When the pistons are moved away from the center of the block 26 on a working stroke, the

fluid in the annular cylinders 34 is forced out of the cylinders 34 into the passages 53, and past ball check valves 54 into an elongated intake manifold passage 55 formed in the block 26. On each intake stroke of the small pistons 36, fluid is drawn from the intake manifold 55 into the small cylinders 37 past ball check valves 56 disposed adjacent passages 58 into the small cylinders 37. On the working stroke of the small pistons 36, fluid is forced through the passages 58 past ball check valves 59 into an outlet manifold passage 60 formed in the block 26. As best shown in FIGURE 6, the check valves 56 and 59 are disposed in passages 57 formed in the piston carriers 32 and adapted to communicate at one end with the intake manifold 55 and at the other eniv ith the outlet manifold 66. it is noted that the intake manifold 55 between the annular cylinder outlet check valves 54 and the small cylinder intake check valves 56 forms an intake chamber of fluid under pressure for the small cylinders 37. The pressure in the intake manifold 55 is limited by a pressure relief valve 65 disposed therein and adapted to bypass any excess fluid to the reservoir.

When the clamping dies are moving toward engagement with a splicing sleeve disposed therebetween the pressure resistance in the pump outlet will be relatively low. As long as the pressure in the outlet manifold 60 is less than the pressure at which the relief valve 65 in the intake manifold 55 is set the fluid pumped by the sleeve pistons 35 will have sufficient pressure to unseat the ball check valves 56 and pass into the outlet manifold 60 along with the output of the small pistons 36 to provide a combined maximum volume output for the pump.

When the clamping dies engage the member to be clamped, the pressure in the outlet manifold 60 automatically increases to a relatively high pressure. As soon as this outlet manifold pressure exceeds the setting of the relief valve 65, the check valves 56 will be held closed during the working strokes of the sleeve pistons 35 and only the output of the small pistons 36 will pass into the outlet manifold 60. Thus, when the pump is Working against a relatively high pressure, the large and small pistons are serially connected with the large pistons merely providing a charge of fluid under pressure for the small pistons 36 and the small pistons providing the high pressure low volume output.

In the embodiment of the pump shown in the drawings, the pressure relief valve 65 is adapted to limit the pressure in the intake manifold 55 and thus, the fluid pressure char e for the small pistons 36 to approximately p.s.i. The small stem pistons 36 are adapted to provide an output up to approximately 10,000 p.s.i. In order to prevent leakage of this high pressure fluid between the piston carriers 32 and the cylinder block 26, a pair of sealing rings 66 and 67 are provided on opposite sides of the connection between each piston carrier passage 57 and the outlet manifold 60.

To provide a selectively variable pump outlet pressure and to insure that the outlet pressure does not exceed a safe value, a pair of safety valves are disposed in the outlet manifold 60 operable to bypass fluid to the reservoir. A pressure relief valve 68 extends horizontally from the block 26 and is adapted to be set at any value between 6000 p.s.i. and 10,000 p.s.i., to limit the pump outlet pressure to a desired value. Another pressure relief or unloading valve 69 operable to open at 11,000 p.s.i. extends downwardly from the block 26 and limits the maximum pressure of the pumping unit to this value.

The portable pumping unit as described herein, when connected to the previously mentioned clamping press will automatically and successively provide, up the starting of the electric motor 10, a relatively high volume low pressure output for advancing the dies, followed by a relatively low volume high pressure output for clamping the dies on a member placed therebetween, and a holding of the relatively high pressure with bypassing of the excess continually pumped fluid through the pressure relief valves to the reservoir.

In order to release the outlet clamping pressure, or to stop the advance of the clamping die at any time, a manual valve is provided between the outlet manifold 69 and the outlet coupling 17. As best shown in FIGURES 2, 4 and 5, and manual valve includes a valve housing 79 disposed in the reservoir and secured to the block 26 by bolts 71. The outlet manifold passage 69 communicates with a flued inlet passage 72 formed in the housing 79 which opens into a stepped bore 73 formed in the valve housing 70, one end of which is adapted to have the outlet coupling 17 connected thereto and the other end of which opens into the reservoir. A pair of ball check valves 74 and 75 are positioned in the stepped bore 73, one on each side of said fluid inlet passage 72 and are adapted to seat on steps formed in the bore 73. A spacer 76 is loosely disposed in the stepped bore 73 between the two ball check valves 74 and 75. The ball check valve 75 positioned adjacent the outlet end of the bore 73 is normally urged into a closed position by a spring 77.

To control the passage of fluid from the outlet manifold 60 past the check valves, a stem or plunger 88 is threadably mounted in the valve housing 79 so as to be selectively engageable with the ball check valve 74. The plunger 89 has a shaft portion 81 extending upwardly through a bore 82 formed in the housing 11 with sealing rings 83 provided to prevent leakage of fluid from the reservoir. A collar 84 carrying a handle portion 85 is threadably secured to the externally projecting end of the shaft portion 81. By using a fast lead thread for mounting the plunger 84 in the valve housing 79, a relatively small degree of rotation of the handle 85 will cause considerable movement of the plunger 89 in the stepped bore 73.

The manual valve handle 85 is adapted to be shifted between three positions (as shown in FIGURE 3) to permit a build-up of pressure in the pump outlet, to hold a pressure in the outlet with bypassing of the pumped fluid to the reservoir, and to allow fluid in the outlet to return to the reservoir to release the clamping pressure. In the first position I of the handle 85, the plunger 80 does not engage the ball check valve 74 so that fluid under pressure unseats the outlet ball check valve 75 against the action of the spring 77 and passes to the outlet coupling 17. In the second position 11 of the handle 85, the plunger 89 moves a limited distance downward to unseat the reservoir ball check valve 74 so as to bypass the pumped fluid to the reservoir, the spring 77 in the outlet acting to close the outlet ball check valve 75 to hold the outlet pressure. In the third position III of the handle 85, the plunger til is moved downward against the reservoir ball check 74 sufliciently to cause the spacer member 76 to unseat the outlet ball check valve 75, thus allowing both fluid in the outlet and that being pumped to pass to the reservoir.

It is believed evident that this manual valve is adapted for use only when the pumping unit is connected to a piston and cylinder device A wherein either a spring s or gravity will return the piston to its initial position when the outlet pressure is released. To use the pumping unit with a piston and cylinder device B wherein fluid pressure is necessary to move the piston in both directions in its cylinder, a modified form of manual valve is used. This modification of the manual valve is shown in FIGURE 8 wherein a second outlet coupling 90 including an Q-ring 99 is fitted in the hole 16 in the housing 11 which in FIG- URES 2, 4 and 5 was shown as blanked. The two outlet couplings 17 and 90 are adapted to be connected by suitable conduits to opposite ends of the piston and cylinder device B being controlled. The valve in this modification has a handle 91 similar to the handle 85 in the first modification which is movable between three positions of advance, neutral, and reverse to selectively provide fluid pressure in opposite ends of the cylinder and piston device B to control the movement thereof. In this modification, a valve block 92 has formed therein a pair of spaced parallel stepped bores 93 and 94 connected together at their adjacent ends by passages 95 and 96 which communicate, respectively, with the two outlet couplings 17 and 90. A fluid inlet passage 97 communicating with the outlet manifold 60 opens into the stepped bore 93 and a passage 98 communicating with the reservoir opens into the stepped bore 94.

A first pair of ball check valves 99 and 100 are disposed in the stepped bore 93 on opposite sides of the fluid inlet passage 97 and a second pair of ball check valves 101 and 102 are disposed in the stepped bore 94 on opposite sides of the passage 98 opening to the reservoir. Spacer members 103 and 104 are disposed, respectively, between the first pair and the second pair of ball check valves. A spring 195 is operable to urge the lower ball check valve 109 to a closed position.

A plunger 1% similar to plunger 80 of the first valve embodiment is mounted in the valve block 92 by a fast lead thread 167, the handle 91 being secured to the upper end of the plunger 196 by a collar 108. With the handle 91 in its first position, the plunger 106 is positioned sufliciently above the upper check valve 99 so that the spring is permitted to close the lower check valve and through thespacer 103 to unseat the upper check valve 99 so as to allow the fluid under pressure to flow from the inlet passage 97 past the upper check valve 99 and out the coupling 98 to one side of the device B being controlled. This inlet pressure in the connecting passage 96 is sufficient to seat the upper check valve 101 in the reservoir bore 94 and consequently through the spacer 104 to unseat the lower check valve 192 to allow fluid to pass from the other side of the device B being controlled past the lower check valve 102 to the reservoir through the passage 98. When the handle 91 is shifted to its second or neutral position, the plunger 106 is shifted downwardly against the upper ball check 99 far enough to cause the spacer 193 to unseat the lower ball check 1% but not far enough the seat the upper ball check 99. Thus, in this neutral position of the handle 91, the fluid under pressure is permitted to flow past both ball checks 99 and 100 and to the reservoir past the ball checks 101 and 192 which are both open as a result of equal pressures in the connecting passages 95 and 96. When the handle 91 is shifted to its third position (shown in FIG. 8), the plunger 106 moves downwardly sufliciently to seat the upper check valve 99 and through the spacer member 193 to open the lower check valve 190 so that pumped fluid may pass through the coupling 17 to the other side of the device B being controlled. The inlet pressure in the passage 95 acts to reverse the second pair of check valves 101 and 102 and allows the fluid in the one side of the device B being controlled to pass to the reservoir.

A modified form of the pumping unit is illustrated in FIGURES 9-12, wherein prior reference numerals primed indicate similar parts. The modifications are generally directed to the intakes for the annular cylinders 34, and to an automatic valve in lieu of the manual valve. As will be apparent from the following description, these modifications are independently applicable to the previously described pumping unit.

The intake structure provides a simplified pump having fewer moving parts and a more positive pumping action, in part, because of a unidirectional flow between the large volume pumping chamber or annular cylinder 34 and the small volume pumping chamber or small cylinder 37.

In the present modification, the intakes for the annular cylinders 34' are in the form of an intake conduit including a hollow retainer or cylinder 115 bolted to the pump block 26' and having a lower open end receiving oil from the reservoir. Oil is forced upwardly by the head of the oil in the reservoir to ports or passages 116 extending through the Walls of large sleeve pistons 117. The ports are opened when the pistons extend outwardly of the in- 4 ner ends of respective cylinders 39. Under these conditions the sleeves, which are telescopically receivable on the tubular portions 33 have their inner ends spaced from the beveled ends of the tubular portions for the passage of oil through the intake passages 116 and into the annular pumping chambers 34.

Opening of the intake passages 116 occurs as they move out of closing engagement with the side surface of the respective cylinder 30 and into the circular recess 31 in response to the urging of spring 47' and movement of the eccentric bearing 46 away from the respective chamber 30'. On the pumping stroke of the piston 117, as the high portion of the eccentric bearing 46 in the central bore in block 26' moves against the piston plate 39, the piston 117 moves into the annular cylinder 34 and the intake passages 116 are closed by the side surface of the cylinder 30.

Discharge of the oil in annular cylinders 34 is through outlet pass-ages 118 and past ball check valves 119 into the manifold 55', and then to the small volume pumping chambers or cylinders 37', or back to the reservoir. Thus, the intake valve, as provided by cooperating portions of the large sleeve pistons 1 17 and the respective outer side surface of annular chamber 34" provides an effective valve means in the intake conduit, and unidirectional flow from the annular chamber 34 to the small volume chamber is therefore provided. The basic operation of the pump is the same as that described in connection with the prior modification, with the exceptions noted immediately above.

Operation of a hydraulic device, such as piston and cylinder device A illustrated in FIGURES 2 and 4, is provided by oil under pressure passing from the pump outlet coupling 17' to the cylinder A. Control of the hydraulic device is eifected by turning the pump on or oil at the electric switch 12. An automatic valve opens for the flow of oil to the cylinder A in response to an adequate oil pressure within the pump, more particularly the pressure of oil in the intermediate manifold 55' passing through a fitting 129 received in a threaded passage intersecting the intermediate manifold 55'. An oil line 121 is connected to the fitting 12d and terminates in an elbow connector communicating with both the automatic valve and a pressure relief valve 122. Oil pressure in the intermediate manifold 55 is limited by the pressure relief valve 122 attached to the automatic valve, in lieu of the pressure relief valve 65 previously described.

The automatic valve is fully described in my prior United States Patent 2,959,009 and will, therefore, be but briefly described herein. Referring to FlGURES and 12, the pump outlet manifold 6h communicates with a valve inlet passage 123 in a valve block 124 which is suitably clamped to the pump housing or cylinder block 26', as by bolts 125. Closing of a ball valve member 126 on a seat at the upper end of an intermediate passage 127 permits oil under pressure to flow from the intermediate manifold 60 through the valve inlet passage 123 and the intermediate passage 127 to a valve outlet passage 128 and through the connector 17 to the hydraulic clamping device cylinder and piston A.

When the pump is inoperative the ball valve member 126 is free to move vertically oif of its seat for the passage of oil from the outlet manifold 6t.- back to the reservoir. A spiral spring 129 received in a socket in the valve block 124 urges a valve-operating lever 13% away from the ball valve member 126 and clockwise about a pin 131 which pivotally mounts the valve operating lever on the valve block 124.

Upon closing the electric switch 12 to start the pump, pressure builds up in the intermediate manifold 55' and is applied through the oil line 121 to a valve closing piston 132 reciprocable in a cylinder in the valve block 124. Responsive to oil pressure in the cylinder, the valve closing piston 132 moves upwardly and a rod portion 133 thereof urges the valve operating lever counterclockwise against the urging of the spring 129 to tightly seat the ball valve member 126 and close the upper end of the intermediate passage 127 for full flow of oil from the outlet manifold 60 through the pump outlet coupling 17.

Rapid opening of the ball valve member 126 is provided by a release ball valve member 134 closable against a seat provided by a stepped portion of a longitudinal passage 139 in the valve closing piston 132. Whenever oil pressure is applied to the piston 132, ball valve 134 is seated. Release of the oil pressure permits a spiral spring 135 to rapidly unseat the valve member 134 for the escape of fluid from the cylinder through the passage 139, around the ball, and through passages 136 in the rod portion 133 to rapidly release the piston and permit unseating of the ball valve member 126.

Pressure relief valve 122 is threaded into the end of a passage 137 communicating with the oil line 121 for limiting the maximum pressure in the intermediate manitold 55 of the pump. Any suitable relief valve may be provided and herein the relief valve includes a spring pressed valve member 138 cooperating with a valve seat on a stepped portion of a longitudinal bore in the relief valve, and opening responsive to a predetermined pressure for the return of oil through passages to the reservoir.

Although this pumping unit was described as if it were connected to a hydraulic clamping press, it is believed evident that the unit is well adapted for use with many other hydraulic devices. A very compact portable pumping unit is provided which at the same time is capable of producing very high output pressures coupled with an initial greater volume of lower pressure output and which only requires an electric motor in the order of /2 HP. to drive the pump. The unit additionally permits the use of high clamping pressures in otherwise inaccessible places.

I claim:

1. A reciprocating piston pum comprising: a pair of opposed pumping units, each unit including means forming a large volume pumping chamber having a large pumping piston reciprocable therein and a small volume pumping chamber having a small pumping piston reciprocable therein; means for moving the pistons of one unit through pumping strokes while the pistons of the other unit move through intake strokes and alternately moving the pistons of the other unit through pumping strokes while the pistons of the one unit move through intake strokes; an intermediate manifold; a discharge manifold; conduit means and valving therein communicaring said large volume chambers with a source of fluid and with said intermediate manifold, whereby a large volume of fluid is pumped from the source to said intermediate manifold by said large pistons; conduit means and valving communicating said intermediate manifold with said small volume chambers and with said discharge manifold whereby said large volume of fluid is pumped by said large pistons from said intermediate manifold partly to said small volume chambers and partly to said discharge manifold and the fluid in said small volume chambers is pumped to the discharge manifold by said small pistons, thereby to provide a large volume flow to the discharge manifold equal to the capacity of the large pistons when the pressure in the discharge manifold is less than that in the intermediate manifold; and a low pressure relief valve in the intermediate manifold for exhausting fluid in excess of the requirements of the small pistons when the pressure in the discharge manifold exceeds that in the intermediate manifold thereby to provide a small volume flow equal to the capacity of the small pistons.

2. A reciprocating piston pump, comprising: a pair of opposed pumping units, each unit including means forming a large volume pumping chamber having a large pumping piston reciprocable therein and a small volume pumping chamber having a small pumping piston reciprocable therein; means for moving the pistons of one unit through pumping strokes while the pistons of the other unit move through intake strokes and alternately moving the pistons of the other unit through pumping strokes while the pistons of the one unit move through intake strokes; a pair of intake conduits leading from a source of fluid respectively to the large volume chambers; an intake valve in each intake conduit; a discharge conduit leading respectively from each large volume chamber, an exhaust valve in each discharge conduit, an intermediate manifold connecting said discharge conduits; a discharge manifold; a pair of intake-discharge conduits leading from the intermediate manifold to the discharge manifold; an intake-discharge port connecting each intake-discharge conduit with one large volume pumping chamber; intake and exhaust valves in each intake-discharge conduit adjacent each intake-discharge port; and a low pressure relief valve in the intermediate manifold.

3. A reciprocating piston pump comprising: a cylinder block; a pair of opposed pumping units in the cylinder block, each unit including means forming a large volume pumping chamber having a large pumping piston reciprocable therein and a small volume pumping chamber having a small pumping piston reciprocable therein; said cylinder block having an intermediate manifold a pair of intake-discharge conduits leading from a source of fluid respectively past the large volume chambers and to said intermediate manifold; an intake-discharge port connecting each intake-discharge conduit with one large volume pumping chamber; intake and exhaust valves in each intake-discharge conduit adjacent each intake-discharge port; said cylinder block having a discharge manifold and a pair of intake-discharge conduits leading from said intermedaite manifold respectively past said small volume chambers to the discharge manifold; an intakedischarge port connecting each last recited intake-discharge conduit with one small volume chamber; intake and exhaust valves in each last recited intake-discharge conduit adjacent each intake-discharge port; a low pres sure relief valve in the intermediate manifold; and means f Jr moving the pistons of one unit through pumping strokes while the pistons of the other unit move through intake strokes and alternately moving the pistons of the other unit through pumping strokes while the pistons of the one unit move through intake strokes, whereby the large pistons pump fiuid from the source through said intermediate manifold and thence partly to said small volume chambers and partly to said discharge manifold and said small pistons pump fluid from the small volume chambers to said discharge manifold thereby to deliver to the discharge manifold a large volume of low pressure fluid when the pressure in the discharge manifold is less than the setting of said relief valve, and whereby the small pistons deliver to the discharge manifold only a small volume of high pressure fluid when the pressure in the discharge manifold exceeds the setting of the relief valve.

4. A pump structure as defined in claim 3, wherein each pumping unit comprises a cylindrically shaped bore in said cylinder block, a cylindrically shaped piston carrier having one end fixed in said bore and having the other end of tubular construction, a large sleeve piston reciprocable on said tubular end, and a small stem piston reciprocable in said tubular end.

5. A reciprocating piston pump comprising: a cylinder block; a pair of opposed pumping units in the cylinder block, each unit including means forming a large volume pumping chamber having a large pumping piston reciprocable therein and a small volume pumping chamber having a small pumping piston reciprocable therein; a reservoir providing a source of fluid; means mounting the cylinder block in the fluid in the reservoir; said cylinder block having an intermediate manifold and a pair of intake-discharge conduits opening to said reservoir and leading respectively past the large volume chambers and to said intermediate manifold; an intake-discharge port connecting each intake-discharge conduit with one large volume pumping chamber; intake and exhaust valves in each intake-discharge conduit adjacent each intake-discharge port; said cylinder block having a discharge manifold and a pair of intake-discharge conduits leading from said intermediate manifold past said small volume chambers to the discharge manifold; an intakedischarge port connecting each last recited intake-discharge conduit with one small volume chamber intake and exhaust valves in each last recited intake-discharge conduit adjacent each intake-discharge port; a low pressure relief valve in the intermediate manifold; means for moving the pistons of one unit through pumping strokes while the pistons of the other unit move through exhaust strokes and alternately moving the pistons of the other unit through pumping strokes While the pistons of the one unit move through intake strokes; and a motor mounted on said reservoir and having a drive shaft connected to actuate said piston moving means.

6. A pump as defined in claim 5, including a high pressure relief valve in the discharge manifold having a setting greatly in excess of the setting of said previously recited low pressure relief valve for exhausting fluid from the discharge manifold to the reservoir when the pressure in the discharge manifold exceeds the higher setting; a discharge conduit leading from said discharge manifold to the outside of the reservoir; and valve means in the discharge conduit having a manually operable handle for controlling the flow of fluid through said discharge conduit to a load device.

7. A reciprocating piston pump, comprising: a pair of opposed pumping units, each unit including means form ing a large volume pumping chamber having a large pumping piston reciprocable therein and a small volume pumping chamber having a small pumping piston reciprocable therein; means for moving the pistons of one unit through pumping strokes while the pistons of the other unit move through intake strokes and alternatively moving the pistons of the other unit through pumping strokes while the pistons of the one unit move through intake strokes; an intermediate manifold; a discharge manifold; intake conduit means and valving communicating said large volume chambers with a source of fluid, said intake valving comprising cooperating valve portions on said piston and means associated with said large volume chamber controlling flow between said intake conduit means and said large volume chamber; outlet conduit means and valving communicating said large volume chambers with said intermediate manifold, whereby a large volume of fluid is pumped from the source to said intermediate manifold by said large pistons; intermediate conduit means and valving communicating said intermediate manifold with said small volume chambers -and with said discharge manifold whereby said large volume of fluid is pumped by said low pressure pistons from said intermediate manifold partly to said small volume chambers and partly to said discharge manifold and the fluid in said small volume chambers is pumped to the discharge manifold by said small pistons, thereby to provide a large volume flow to the discharge manifold equal to the capacity of the large pistons when the pressure in the discharge manifold is less than that in the intermediate manifold; and a low pressure relief valve in the intermediate manifold for exhausting fluid in excess of the requirements of the small pistons when the pressure in the discharge manifold exceeds that in the intermediate manifold thereby to provide a small volume flow equal to the small pistons.

8. A reciprocating pump comprising: a cylinder block; a pair of opposed pumping units in the cylinder block; each unit including means having a cylindrically shaped bore defined by a cylindrical surface in said cylinder block and forming a large volume pumping chamber; a cylindrical shaped piston carrier having one end fixed in said bore and having the other end of tubular construction defining a Small volume pumping chamber and spaced from said cylindrical surface; a large sleeve piston reciprocal on said tubular end and in said large volume pumping chamber; a small stern piston reciprocal in said tubular end; a source of fluid; intake conduit means communicable with said large volume pumping chambers; valving means in said intake conduit means comprising port means in each large sleeve piston cooperating with said cylindrical surfaces closing said intake conduit means to the respective large volume chamber during a portion of the stroke of said large sleeve piston and opening said conduit means during another portion of the stroke, and a passage between said tubular end and said large sleeve piston when said intake conduit means is open to the respective large volume chamber; said cylinder block having an intermediate manifold; a discharge passage connecting each large volume pumping chamber with said intermediate manifold; a check valve in each discharge passage to prevent back flow into the large volume pumping chambers; said cylinder block having a discharge manifold and a pair of intakedischarge conduits leading from said intermediate manifold respectively past said small volume chambers to the discharge manifold; an intake-discharge port connecting each intake-discharge conduit with one small volume chamber; intake and exhaust valves in each intake-discharge conduit adjacent each intake-discharge port; a low pressure relief valve communicating with the intermediate manifold; and means for moving the pistons of one unit through pumping strokes while the pistons of the other unit move through intakes strokes and alternately moving the pistons of the other unit through pumping strokes While the pistons of the one unit move through intake strokes, whereby the large sleeve pistons pump fluid from the source through said intermediate manifold and thence partly to said small volume chambers and partly to said discharge manifold and said small stern pistons pump fluid from the small volume chambers to said discharge manifold thereby to deliver to the discharge manifold a large volume of low pressure fluid when the pressure in the discharge manifold is less than the setting of said relief valve, and whereby the small stem pistons deliver to the discharge manifold only a small volume of high pressure fluid when the pressure in the discharge manifold exceeds the setting of the relief valve.

9. A reciprocating pump comprising: a cylinder block; a pair of opposed pumping units in the cylinder block; each unit including means having a cylindrically shaped bore defined by a cylindrical surface in said cylinder block and forming a large volume pumping chamber; a cylindrical shaped piston carrier having one end fixed in said bore and having the other end of tubular construction defining a small volume pumping chamber and spaced from said cylindrical surface; a large sleeve piston reciprocal on said tubular end and in said large volume pumping chamber; a small stern piston reciprocal in said tubular end; a source of fluid; intake conduit means comprising a recess in said cylinder block communicable with said large volume pumping chambers; valving means in said intake conduit means comprising port means in each large sleeve piston cooperating with said cylindrical surfaces closing said intake conduit means to the respective large volume chamber during a portion of the stroke of said large sleeve piston and opening said conduit means during another portion of the stroke, and a passage between said tubular end and said large sleeve piston when said intake conduit means is open to the respective large volume chamber; said cylinder block having an intermediate manifold; a discharge passage connecting each large volume pumping chamber with said intermediate manifold; a check valve in each discharge passage to prevent back flow into the large volume pumping chambers; said cylinder block having a discharge manifold and a pair of intake-discharge conduits leading from said intermediate manifold respectively past said small volume chambers to the discharge manifold; an intake-discharge port connecting each intake-discharge conduit with one small volume chamber; intake and exhaust valves in each intake-discharge conduit adjacent each intake-discharge port; a low pressure relief valve communicating with the intermediate manifold; and means in said recess for moving the pistons through pumping strokes and intake strokes whereby the large sleeve piston pumps fluid from the source through said intermediate manifold and thence partly to said small volume chamber and partly to said discharge manifold and said small stem piston pumps fluid from the small volume chamber to said discharge manifold thereby to deliver to the discharge manifold a large volume of low pressure fluid when the pressure in the discharge manifold is less than the setting of said relief valve, and whereby the small stern piston delivers to the discharge manifold only a small volume of high pressure fluid when the pressure in the discharge manifold exceeds the setting of the relief valve. 7

10. A reciprocating pump comprising: a cylinder block; a pumping unit in said cylinder block, said pumping unit including means having a cylindrically shaped bore defined by a cylindrical surface in said cylinder block and forming a pumping chamber; a cylindrical shaped piston carrier having one end fixed in said bore and having the other end of stem construction spaced from said cylindrical surface; a sleeve piston reciprocal on said end and in said pumping chamber; a source of fluid; intake conduit means communicable with said pumping chamber; valve means in said intake conduit means and comprising a port in said sleeve piston coopcrating with said cylindrical surface closing said intake conduit means to the pumping chamber during the pumping stroke of said sleeve piston and opening said conduit means during the intake stroke, and a passage between said end and said sleeve piston when said intake conduit means is open to the pumping chamber; means providing for the passage of fluid from said pumping chamber during the pumping stroke; and means for moving the piston through pumping strokes and intake strokes.

11. A reciprocating pump comprising: a cylinder block; a pumping unit in said cylinder block, said pumping unit including means having a cylindrically shaped bore defined by a cylindrical surface in said cylinder block and forming a large volume pumping chamber; a cylindrical shaped piston carrier having one end fixed in said bore and having the other end of tubular construction defining a small volume pumping chamber and spaced from said cylindrical surface; a large sleeve piston reciprocal on said tubular end and in said large volume pumping chamber; a small stem piston reciprocal in said tubular end; a source of fluid; intake conduit means communicable with said large volume pumping chamber; valve means in said intake conduit means and comprising a port in said large sleeve piston cooperating with said cylindrical surface closing said intake conduit means to the respective large volume chamber during a portion of the stroke of said large sleeve piston and opening said conduit means during another portion of the stroke, and a passage between said tubular end and said large sleeve piston when said intake conduit means is open to the large volume chamber; and means for the passage of fluid from said large volume pumping chamber to said small volume pumping chamber.

12. A reciprocating pump comprising: a cylinder block; a pair of opposed pumping units in the cylinder block; each unit including means having a cylindrically shaped bore defined by a cylindrical surface in said cylinder block and forming a large volume pumping chamber; a cylindrical shaped piston carrier having one 13 end fixed in said bore and having the other end of tubular construction defining a small volume pumping chamber and spaced from said cylindrical surface; a large sleeve piston reciprocal on said tubular end and in said large volume pumping chamber; a small stem piston reciprocal in said tubular end; a source of fluid; intake conduit means comprising a recess in said cylinder block communicable with said large volume pumping chambers; valving means in said intake conduit means comprising port means in said large sleeve piston cooperating with said cylindrical surface closing said intake conduit means to the large volume chamber during a portion of the stroke of said large sleeve piston and opening said conduit means during another portion of the stroke; a passage between said tubular end and said large sleeve piston when said intake conduit means is open to the respective large volume chamber; means for the passage of fluid from said large volume pumping chambers to said small volume pumping chambers; means to prevent backfiow from said small volume pumping chambers to said large volume pumping chambers; and means in said recess for reciprocally driving said pistons.

References (Iited in the file of this patent UNITED STATES PATENTS 1,868,498 Gruman July 26, 1932 FOREIGN PATENTS 834,915 Great Britain May 11, 1960 

